.clearfix:after{
    content: "";
    display: block;   
    overflow: hidden;
    clear: both;
}
.clearfix{
    zoom: 1;
}
.fl{
    float: left;
}
.fr{
    float: right;
}
body{
    width: 10rem;
    background: #eee;
    margin: 0 auto;
}